Case Study: Monitoring Particle Shed of Process Tools with the Chem 20 Particle Counter
A Quick Overview
Wet process equipment is used in semiconductor manufacturing facilities with a variety of chemicals for cleaning, etching, plating, developing, and other wet process applications. Such tools are likely to contain many active components, including pumps, filters and valves, that can generate or shed particle contamination. The tools also contain many internal surfaces that can act as particle ‘traps’, increasing cleaning time. As a result, process tools can require a significant amount of flushing post-manufacture before use in production. To improve yield, Semiconductor Particle Contamination Control is critical.
Studying Process Tool Impact on Semiconductor Particle Contamination
Particle measurements, using the 20 nm chemical particle counter Chem 20 from Particle Measuring Systems, were taken on:
- The fluid going into the wet process tool (Sample point 1), which is filtered immediately upstream to 5 nm.
- The fluid coming out of the tool (Sample point 2).
With this data, we can determine how many particles are being added to the outgoing fluid by the tool. The results for both sample points after approximately 10 hours of flushing are summarized below.
The particle concentration measured at Sample point 1 was very low, as would be expected immediately downstream from a 5 nm filter. However, the particle concentration at Sample point 2 increased by several orders of magnitude, indicating this tool was shedding particles even after ten hours of flushing. For tool manufacturers that flush until their requirements are met, the Chem 20 chemical particle counter can check particle qualifications in real-time.
Troubleshooting Points of Particle Contamination
The Chem 20 chemical particle counter isn’t just for qualification and particle cleanliness tests. It can also troubleshoot particle contamination issues and identify highly contaminating components for replacement. A comparison of particle measurements performed on a photoresist coater and developer track is shown below.
In this setup, the Chem 20 particle counter sampled a proprietary photoresist thinning agent connected to the point of use at the chemical dispensing nozzle. Since this chemical produced high amounts of molecular scattering, the Chem 20 particle counter operated in high-scatter mode with the size sensitivity reduced slightly to 24 nm. SP5 wafer scanning tests were also taken in parallel.
Semiconductor Particle Contamination Control Case Study Results
Both the Chem 20 chemical particle counter and SP5 analysis measured a significantly higher number of particle counts at Track B than at Track A. After some troubleshooting, an aging manifold block within Track B was replaced and the measurement repeated. The particle concentration decreased by one order of magnitude (lower than Track A) after replacing the manifold block. The Chem 20 particle counter measurements were consistent with the SP5 wafer scanning results. The SP5 tests detected a higher number of particles during each test, since the number of smaller particles included was higher.
Wet process equipment contains many components that are potential sources of particle contamination, and the ability to troubleshoot highly contaminating components in real-time without the need for offline laboratory analysis offers a significant benefit to equipment manufacturers.
Will the Chem 20 Chemical Particle Counter Work for My Process?
The Chem 20 particle counter has been used successfully for the control and mitigation of yield-impacting nanoparticle contamination in process chemicals throughout the microelectronic industry. The examples presented in this blog series are just the beginning. The Chem 20 chemical particle counter can be used for a broad range of applications, and yours might just be a perfect fit.
The cleanliness of chemical media, process tools and materials used in semiconductor manufacturing plays a large role in the yield of these devices. With industry-leading 20 nm sensitivity, the Chem 20 particle counter provides the ability to detect particles as close to the critical dimension size as possible.
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